Durable fire retardant for forest and rangelands

Abstract

A concentrated ammonium salt composition containing a binder and viscosity control agent usable in aqueous dispersion. The dispersion is applied to foliage and vegetation to hinder or prevent wildfires for one complete season.

The embodiments of this invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. A concentrated ammonium salt composition suitable for use in the manufacture of aqueous weather-durable fire retardants which comprises: (a) From about 20 to 70 percent by weight of an ammonium salt selected from the group consisting of monoammonium orthophosphate, diammonium orthophosphate, monoammonium-alkali metal mixed orthophosphates, diammonium-alkali metal mixed orthophosphates, ammonium-alkaline earth metal mixed orthophosphates, ammonium sulfate, substantially water-insoluble ammonium polyphosphates, and mixtures thereof, wherein said ammonium polyphosphates are represented by the formula   H.sub.(n-m)+2 (NH.sub.4).sub.m P.sub.n O.sub.3n+1        wherein n is an integer having an average value from 20 to about 400, m/n has an average value between about 0.7 and about 1.1, and m has a maximum value equal to n+2;   (b) from about 20 to 70 percent by weight of a reactive, water-soluble binder which insolubilizes upon drying; and   (c) from about 1 to 10 percent by weight of a water-dispersible, viscosity control agent which imparts thixotropic flow properties to an aqueous dispersion of said composition.   
     
     
       2. A concentrated ammonium salt composition suitable for use in the manufacture of aqueous weather-durable fire retardants which comprises: (a) From about 30 to 60 percent by weight of an ammonium salt selected from the group consisting of monoammonium orthophosphate, diammonium orthophosphate, monoammonium-alkali metal mixed orthophosphates, diammonium-alkali metal mixed orthophosphates, ammonium-alkaline earth metal mixed orthophosphates, ammonium sulfate, substantially water-insoluble ammonium polyphosphates, and mixtures thereof, wherein said ammonium polyphosphates are represented by the formula   H.sub.(n-m)+2 (NH.sub.4).sub.m P.sub.n O.sub.3n+1        wherein n is an integer having an average value from 20 to about 400, m/n has an averge value between about 0.7 and about 1.1, and m has a maximum value equal to n+2;   (b) from about 30 to 60 percent by weight of a melamine resin binder; and   (c) from about 2 to 6 percent by weight of a cross-linked olefin-maleic anhydride interpolymer.   
     
     
       3. A composition of claim 2 wherein the ammonium salt is diammonium orthophosphate, ammonium polyphosphate, or a mixture thereof, and the interpolymer is ethylene-maleic anhydride. 
     
     
       4. A weather-durable fire retardant composition which comprises an aqueous dispersion of (a) An ammonium salt selected from the group consisting of monoammonium orthophosphate, diammonium orthophosphate, monoammonium-alkali metal mixed orthophosphates, diammonium-alkali metal mixed orthophosphates, ammonium-alkaline earth metal mixed orthophosphates, ammonium sulfate, substantially water-insoluble ammonium polyphosphates, and mixtures thereof, wherein said ammonium polyphosphates are represented by the formula   H.sub.(n-m)+2 (NH.sub.4).sub.m P.sub.n O.sub.3n+1        wherein n is an integer having an average value from 20 to about 400, m/n has an average value between about 0.7 and about 1.1, and m has a maximum value equal to n+2.   (b) a reactive, water-soluble binder which insolubilizes upon drying; and   (c) a water-dispersible, viscosity control agent which imparts thixotropic flow properties to an aqueous dispersion, wherein (a), (b) and (c) together comprise from about 5 to 40 percent by weight of said aqueous dispersion.     
     
     
       5. An aqueous weather-durable fire retardant composition which comprises: (a) From about 2 to 20 percent by weight of an ammonium salt selected from the group consisting of monoammonium orthophosphate, diammonium orthophosphate, monoammonium-alkali metal mixed orthophosphates, diammonium-alkali metal mixed orthophosphates, ammonium-alkaline earth metal mixed orthophosphates, ammonium sulfate, substantially water-insoluble ammonium polyphosphates, and mixtures thereof, wherein said ammonium polyphosphates are represented by the formula   H.sub.(n-m)+2 (NH.sub.4).sub.m P.sub.n O.sub.3n+1        wherein n is an integer having an average value from 20 to about 400, m/n has an average value between about 0.7 and about 1.1, and m has a maximum value equal to n+2;   (b) from about 2 to 20 percent by weight of a reactive, water-soluble binder which insolubilizes upon drying; and   (c) from about 0.1 to 5 percent by weight of a water-dispersible viscosity control agent which imparts thixotropic flow properties to said composition.   
     
     
       6. An aqueous composition of claim 5 wherein the ammonium salt is diammonium orthophosphate, ammonium polyphosphate, or a mixture thereof; the binder is a melamine resin; and the viscosity control agent is a cross-linked C 2  -C 4  olefin-maleic anhydride interpolymer.